Different effects of nicotine, dimethylphenylpiperazinium and tetramethylammonium on smooth muscle preparations from the body of human and feline stomach

Abstract

Effects of the gaglionic stimulants, nicotine, dimethylphenylpiperazinium and tetramethylammonium on the isolated strips of longitudinal and circular muscles from the body of human and feline stomach were investigated. Tetramethylammonium produced concentration-dependent contractions of isolated preparations of either longitudinal or circular muscles of both species. Nicotine induced concentration-dependent relaxation only of the feline circular muscle strips. On the other hand, dimethylphenylpiperazinium had no significant effects on isolated strips of the longitudinal and circular muscles from the body of human and feline stomach. The differences in the effects of the ganglionic stimulants most probably reflect distinct anatomical sites of actions as well as nicotinic and muscarinic receptors in nervous structures and possibly smooth muscles of the human and feline gastric body. In addition, the ability of nicotine, but not of dimethylphenylpiperazinium and tetramethylammonium, to relax only the circular strips of the feline gastric body might indicate the existence of an unusual subtype of nicotinic receptors through which nicotine stimulates the inhibitory enteric ganglia.